Color perception is a product of the fact that light is made up of many different wavelengths. Each wavelength, or frequency, of light represents a different color. The color of an object can be defined very precisely, by the percent of reflectance of each respective wavelength of incident light. This measure of a color of an object is known as a spectrophotometric reading. In simple terms, a red object appears red because it reflects relatively more red light than non-red light.
The human eye, however, is not capable of resolving all the levels of color detail. Due to the way that the retina of the eye senses light, the spectrophotometric reading is reduced to three values, one each corresponding to band pass filters in the red, green, and blue areas of the spectrum. In this manner, the human eye is discarding a great deal of the spectrophotometric data when perceiving a particular object color.
It is also known that many color blind persons also see three bands of color, but they are different bands from the normal red, green, and blue areas in normal vision. Therefore, color blind persons and non color blind persons see the world in different colors.